Voice coil motor

ABSTRACT

The VCM according to an exemplary embodiment of the present disclosure includes a base unit, a mover including a bobbin arranged at an upper surface of the base unit and formed with a plurality of rotation prevention units along a periphery and a first driving unit arranged at a periphery of the bobbin, a stator including a yoke configured to the base unit to surround the mover and inner yoke units each extended to between the rotation prevention units, and a second driving unit oppositely arranged to the first driving unit, and an elastic member elastically supporting the mover, wherein an object occurrence preventing portion is formed between the rotation prevention unit and the inner yoke units to decrease a contact area between the rotation prevention unit and the inner yoke units.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation Applications of U.S. patent application Ser. No. 17/029,419, filed Sep. 23, 2020, which is a Continuation Applications of U.S. patent application Ser. No. 16/783,664 filed Feb. 6, 2020 (now U.S. Pat. No. 10,819,208), which is a Continuation Applications of U.S. patent application Ser. No. 16/269,782, filed Feb. 7, 2019 (now U.S. Pat. No. 10,587,179), which is a Continuation Applications of U.S. patent application Ser. No. 15/784,365 filed Oct. 16, 2017 (now U.S. Pat. No. 10,263,502), which is a Continuation Applications of U.S. patent application Ser. No. 14/419,780, filed on Feb. 5, 2015 (now U.S. Pat. No. 9,819,254), which is a U.S National Stage Application under 35 U.S.C. § 371 of PCT Application No. PCT/KR2013/005624, filed Jun. 26, 2013, which claims priority to Korean Patent Application No. 10-2012-0097323, filed Sep. 3, 2012, the subject matter of which are incorporated herein by reference.

TECHNICAL FIELD

The teachings in accordance with exemplary and non-limiting embodiments of this disclosure relate generally to a VCM.

BACKGROUND ART

Recently, mobile communication devices such as mobile phones, game machines and tablet PCs are mounted with camera modules including image sensors capable of storing an object in a digital still image or a video image.

A conventional camera module suffers from disadvantages in that that it is difficult to adjust a gap between an image sensor and a lens arranged at a front surface of the image sensor, and it is also difficult to accurately adjust a focus on an object, resulting in an image quality degradation of the digital image or video.

Concomitant with a recent development of a VCM (Voice Coil Motor), a gap between a lens and an image sensor can be adjusted to obtain an excellent digital image or a video. In order to drive a VCM, the VCM includes a stator including a magnet an a yoke, a rotor including a coil block arranged inside the stator and arranged at a periphery of a bobbin mounted with a lens to generate an electromagnetic force in response to a driving current applied from an outside, and a cover arranged at the stator to cover the rotor.

The conventional VCM however suffers from disadvantages in that, although a portion of a bobbin is hitched at a yoke to prevent the bobbin from rotating abnormally, the bobbin contacted to the yoke allows the bobbin to generate particles such as fine dust or fine objects, and the fine objects are in turn collected at an IR (Infrared) filter arranged at a bottom surface of the bobbin to deteriorate a display quality of an image or a video.

The present disclosure is to provide a VCM configured to decrease or inhibit generation of objects from a bobbin in a case a yoke and the bobbin are contacted, whereby a display quality degradation of an image or a video can be prevented.

Technical problems to be solved by the present disclosure are not restricted to the above-mentioned descriptions, and any other technical problems not mentioned so far will be clearly appreciated from the following description by skilled in the art.

In one exemplary embodiment of the present disclosure, there is provided a VCM, the VCM comprising:

a base unit, a mover including a bobbin arranged at an upper surface of the base unit and formed with a plurality of rotation prevention units along a periphery and a first driving unit arranged at a periphery of the bobbin, a stator including a yoke configured to the base unit to surround the mover and inner yoke units each extended to between the rotation prevention units, and a second driving unit oppositely arranged to the first driving unit, and an elastic member elastically supporting the mover, wherein an object occurrence preventing portion is formed between the rotation prevention unit and the inner yoke units to decrease a contact area between the rotation prevention unit and the inner yoke units.

A VCM according to an exemplary embodiment of the present disclosure has an advantageous effect in that a contact area between a rotation prevention unit of a bobbin and an inner yoke unit of a yoke contacting the rotation prevention unit of the bobbin is reduced to decrease or inhibit generation of objects generated from the rotation prevention unit when the rotation prevention unit of the bobbin and the inner yoke unit are brought into contact, whereby quality degradation of an image or a video can be prevented.

DESCRIPTION OF DRAWINGS

FIG. 1 is a cross-sectional view illustrating a VCM according to an exemplary embodiment of the present disclosure.

FIG. 2 is an enlarged view of ‘A’ of FIG. 1 .

FIG. 3 is a lateral view of a bobbin of FIG. 1 .

FIG. 4 is a perspective view illustrating a bobbin according to another exemplary embodiment of the present disclosure.

DETAILED DESCRIPTION

The disclosed exemplary embodiments and advantages thereof are best understood by referring to the accompanying drawings. Like numbers refer to like elements throughout. In the figures, certain layers, sizes, shapes, components or features may be exaggerated for clarity and convenience.

Accordingly, the meaning of specific terms or words used in the specification and claims should not be limited to the literal or commonly employed sense, but should be construed or may be different in accordance with the intention of a user or an operator and customary usages. Therefore, the definition of the specific terms or words should be based on the contents across the specification.

FIG. 1 is a cross-sectional view illustrating a VCM according to an exemplary embodiment of the present disclosure, FIG. 2 is an enlarged view of ‘A’ of FIG. 1 , and FIG. 3 is a lateral view of a bobbin of FIG. 1 .

Referring to FIGS. 1, 2 and 3 , a VCM (600) includes a base unit (100), a mover (200), a stator (300), an elastic member (400) and an object occurrence preventing portion (500).

The base unit (100) takes a shape of a cubic plate, and is centrally formed with a through hole (110) passing through an upper surface of the base unit (100) and a bottom surface opposite to the upper surface. Each of four corners formed on the upper surface of the base unit (100) is coupled to a coupling pillar (120), where the coupling pillar (120) is coupled to a spacer (330, described later). The mover (200) includes a bobbin (210) and a first driving unit (220).

The bobbin (210) takes a shape of a cylinder opened at an upper surface and a bottom surface, and may be formed at an inner surface with a female screw unit (212) for mounting at least one cylindrical lens. The bobbin (210) is protrusively formed at a periphery (211) with a plurality of rotation prevention units (213) along the periphery (211) of the bobbin (210), where four rotation prevention units (213) may be formed along the periphery (211) of the bobbin (210), each spaced apart at a predetermined distance.

The rotation prevention units (213) prevent the rotation of the bobbin (210) by being hitched by an inner yoke portion (323) of a yoke (320, described later).

Although the exemplary embodiment of the present disclosure has described a plurality of rotation prevention units (213) protruded from the periphery (211) of the bobbin (210) each spaced apart at a predetermined distance, alternatively, it should be apparent that each of the rotation prevention units (213) formed on the bobbin 210) may take a recess shape concaved from the periphery (211) of the bobbin (210).

The first driving unit (220) is formed by winding a long wire insulated by an insulating resin, and may be bonded to a surface of the rotation prevention unit (213) of the bobbin (210) using an adhesive. The stator (300) includes a second driving unit (310) and a yoke (320). In addition, the stator (300) may include a spacer (330).

In the exemplary embodiment of the present disclosure, the second driving unit (310) is arranged at an outside of the first driving unit (220). The second driving unit (310) is arranged opposite to the first driving unit (220). The second driving unit (310) includes four magnets in a shape of a pillar, for example, and the four pillar-like magnets are formed about the first driving unit (220), each spaced apart at a predetermined distance.

The yoke (320) is formed in a shape of a square plate, and includes a yoke upper plate (321) centrally formed with a round opening and yoke lateral plates (322) extended from four edges of the yoke upper plate (321) to wrap the mover (100). Each of inner corners formed by a pair of adjacent yoke lateral plates (322) is arranged with the second driving unit (310). The yoke upper plate (321) is formed with an inner yoke unit (323) extended from the opening of the yoke upper plate (321) to the rotation prevention units (213) of the bobbin (210).

The inner yoke unit (323) functions to prevent the bobbin (210) from rotating by being contacted to the rotation prevention unit (213) in a case the bobbin (210) is rotated by leakage of electromagnetic field generated by the first driving unit (220) and turning effect generated in a case a lens is mounted to the bobbin (210).

The elastic member (400) is arranged at a bottom surface of the bobbin (210) of the mover (200). In the exemplary embodiment of the present invention, the elastic member (400) may be formed in a pair, and each of the elastic members (400) is electrically insulated. The pair of elastic members (400) includes an inner elastic unit (410), an outer elastic unit (420) and a connection elastic unit (430).

The outer elastic unit (420), when seen in a top plan view, takes a shape of a bent strip, and is coupled to the coupling pillar (120) by being inserted into a pair of adjacent coupling pillars (120) of the base unit (100). The inner elastic unit (410) is arranged at a bottom surface of the bobbin (210). Thus, the inner elastic unit (410) takes a shape of a curved strip similar in shape to the bottom surface of the bobbin (210). The connection elastic unit (430), when seen in a top plan view, is formed in a zigzag shape to be connected to the inner and outer elastic units (410, 420).

Referring to FIG. 1 again, an upper surface opposite to the bottom surface of the bobbin (210) is arranged with an additional elastic member (450) elastically supporting the bobbin (210). The spacer (330) serves to fix the elastic member (400), the additional elastic member (450), the mover (200) and the stator (300). The spacer (330) includes an upper spacer (332) and a bottom spacer (335), where the upper and bottom spacers (332, 335) are meshed. The bottom spacer (335) is coupled to the coupling pillars (120) of the base unit (100). The outer elastic unit (420) of the elastic member (400) is fixed between the bottom spacer (335) and an upper surface of the base unit (100), and the additional elastic member (450) is fixed to a bottom surface of the upper spacer (332).

A cover (550) includes a cover upper plate (560) formed in a shape of a square plate having a round opening for exposing a lens and a cover lateral plate (570) extended from an edge of the cover upper plate (560). The cover lateral plate (570) is coupled to the base unit (100).

Referring to FIGS. 2 and 3 , the bobbin (210) is applied with a turning effect in a case a lens is coupled to the bobbin (210), or the bobbin (210) vertically moves, and the bobbin (210) is horizontally rotated by the turning effect applied to the bobbin (210). At this time, in a case the bobbin (210) is rotated, the elastic member (400) and the additional elastic member (450) are deformed or twisted to twist an optical axis of the mover (200) or to generate a driving defect of the mover (200).

As noted from the foregoing, the rotation of bobbin (210) is prevented by the rotation prevention unit (213) formed at the periphery of the bobbin (210) and the inner yoke unit (323) of the yoke (320), where, in a case the inner yoke unit (323) and the rotation prevention unit (213) are brought into contact, a fine objects may be generated from the bobbin (210) which is a molded material, and the fine objects may drop to be introduced to an upper surface of an IR (Infrared) filter arranged at a rear surface of the base unit (100).

In a case the fine objects generated from the bobbin (210) are introduced to an upper surface of an IR (Infrared) filter, there may be generated a quality degradation of a digital image or a video due to the fine objects.

In the exemplary embodiment of the present disclosure, the VCM (600) includes the object occurrence preventing portions (500) preventing generation of objects by contact between the rotation prevention unit (213) of the bobbin (210) and the inner yoke unit (323) of the yoke (320). The object occurrence preventing portions (500) reduce or inhibit, for example, a generated amount of fine objects from the rotation prevention unit (213) by reducing a contact area between the rotation prevention unit (213) of the bobbin (210) and the inner yoke unit (3230 of the yoke (320). The object occurrence preventing portion (500) is formed at each lateral surface (213 a) of the rotation prevention unit (213) opposite to both lateral surfaces of the inner yoke unit (323) and contacting the inner yoke unit (323).

Particularly, the object occurrence preventing portion (500) formed on the lateral surfaces (213 a) opposite to both lateral surfaces of the inner yoke unit (323) is formed in a shape of a staircase extended outwardly from the rotation prevention unit (213) for reducing the generated amount of fine objects from the rotation prevention unit (213).

To be more specific, in a case the both lateral surfaces of the inner yoke unit (323) are formed in a shape of a straight line, a first gap is formed between the lateral surfaces of the rotation prevention unit (213) and the lateral surfaces of the inner yoke unit (323), and a second gap greater than the first gap is formed between the lateral surfaces of the object occurrence preventing portion (500) and the inner yoke unit (323).

Hence, in a case the bobbin (210) is rotated, the lateral surfaces of the inner yoke unit (323) are brought into contact with each lateral surface (213 a) of the area-reduced rotation prevention unit (213), whereby the generated amount of objects can be reduced or inhibited by the rotation prevention unit (213). Furthermore, in view of the fact that the bobbin (210) is injection-molded, the object occurrence preventing portion (500) may be formed at a predetermined depth from an upper surface of the bobbin (210).

Meanwhile, in a case the object occurrence preventing portion (500) is formed using an injection molding method, albeit being difficult, the object occurrence preventing portion (500) may be intermittently formed with at least two rotation prevention units (213) in order to reduce a contact area between the rotation prevention unit (213) of the bobbin (210) and the inner yoke unit (323).

Now, referring to FIG. 4 , even if the amount of objects generated by contact between the rotation prevention unit (213) and the inner yoke unit (323) in response to the rotation of bobbin (210) may be reduced or inhibited by the object occurrence preventing portion (500), a small amount of objects can be generated, such that, in the exemplary embodiment of the present disclosure, an object collecting member (590) may be formed at a floor surface of a groove formed by the rotation prevention unit (213) in order to prevent a small amount of objects generated from the rotation prevention unit (213) from entering the IR filter.

The object collecting member (590) may include a synthetic resin, for example, having a sufficient viscosity for collecting the foreign objects. The object collecting member (590) may include an epoxy resin having a viscosity.

Although the exemplary embodiment of the present disclosure has described and explained the reduction or inhibition of fine objects of the rotation prevention unit (213) of the bobbin (210) by forming a recess-shaped object occurrence preventing portion (500) on the rotation prevention unit (213) of the bobbin (210), alternatively, a portion of the inner yoke unit (323) of the yoke (320) opposite to the rotation prevention unit (213) may be cut to reduce a contact area with the rotation prevention unit (213). Furthermore, in a case an object occurrence preventing portion is formed at a lateral surface of the inner yoke unit (323), a plurality of object occurrence preventing portions may be intermittently formed along the lateral surface of the inner yoke unit (323).

As apparent from the foregoing, a contact area between a rotation prevention unit of a bobbin and an inner yoke unit of a yoke contacting the rotation prevention unit of the bobbin is reduced to decrease or inhibit generation of objects generated from the rotation prevention unit when the rotation prevention unit of the bobbin and the inner yoke unit are brought into contact, whereby quality degradation of an image or a video can be prevented.

The previous description of the present disclosure is provided to enable any person skilled in the art to make or use the disclosure. Various modifications to the disclosure will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other variations without departing from the spirit or scope of the disclosure. Thus, the disclosure is not intended to limit the examples described herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein. 

What is claimed is:
 1. A voice coil motor comprising: a base unit; a yoke disposed on the base unit; a bobbin disposed in the yoke; a coil and a magnet disposed in the yoke and configured to move the bobbin in an optical axis direction; and an upper elastic member coupled to the bobbin, wherein the bobbin comprises an upper surface disposed with the upper elastic member, and first and second recesses recessed from the upper surface of the bobbin, wherein the second recess is recessed deeper than the first recess from the upper surface of the bobbin, wherein the yoke comprises an inner yoke, wherein at least a portion of the inner yoke is disposed in the second recess, wherein the first recess is disposed next to the second recess so that the first recess is connected to the second recess when viewed from outside the bobbin, wherein the portion of the inner yoke is overlapped by a part of the bobbin in a direction perpendicular to a first direction parallel to the optical axis direction and a second direction from the second recess to the optical axis, and wherein the portion of the inner yoke is disposed between the coil and the part of the bobbin.
 2. The voice coil motor of claim 1, wherein the first recess comprises a first surface facing a same direction with the upper surface of the bobbin, and wherein the first surface of the first recess is disposed at a position lower than the upper surface of the bobbin.
 3. The voice coil motor of claim 2, wherein the second recess comprises a first surface facing the same direction with the upper surface of the bobbin, and wherein the first surface of the second recess is disposed at a position lower than the first surface of the first recess.
 4. The voice coil motor of claim 3, wherein a first step is formed by the upper surface of the bobbin and the first surface of the first recess, and wherein a second step is formed by the first surface of the first recess and the first surface of the second recess.
 5. The voice coil motor of claim 3, wherein, in the optical axis direction, a distance between the first surface of the first recess and the first surface of the second recess is greater than a distance between the upper surface of the bobbin and the first surface of the first recess.
 6. The voice coil motor of claim 1, wherein the coil is disposed on an outer peripheral surface of the bobbin, wherein the second recess is recessed from the outer peripheral surface of the bobbin so that a space is formed between the bobbin and the coil, and wherein at least a portion of the inner yoke is disposed in the space between the bobbin and the coil.
 7. The voice coil motor of claim 1, wherein the bobbin comprises a plurality of rotation prevention units, and wherein the second recess is disposed between the plurality of rotation prevention units.
 8. The voice coil motor of claim 7, wherein the inner yoke is contacted to the rotation prevention unit of the bobbin when the bobbin is rotated about the optical axis.
 9. The voice coil motor of claim 8, wherein the first recess is an object occurrence preventing portion configured to decrease a contact area between the rotation prevention unit of the bobbin and the inner yoke.
 10. The voice coil motor of claim 1, wherein the first recess is overlapped with the inner yoke in a circumferential direction about the optical axis.
 11. The voice coil motor of claim 1, wherein the first recess is disposed at both sides of the inner yoke in a circumferential direction about the optical axis.
 12. The voice coil motor of claim 1, wherein, in a direction perpendicular to the optical axis and facing from the optical axis toward outside, at least a portion of the inner yoke is disposed between the bobbin and the coil.
 13. The voice coil motor of claim 1, wherein the inner yoke comprises at least two inner yokes spaced apart from each other.
 14. The voice coil motor of claim 1, wherein the yoke comprises a lateral plate disposed on the base unit, and wherein the magnet is directly disposed on inner surface of the lateral plate of the yoke.
 15. The voice coil motor of claim 1, comprising a lower elastic member coupled to a lower portion of the bobbin and formed as a pair spaced apart from each other.
 16. A camera module, comprising the voice coil motor of claim 1; a lens coupled to the bobbin of the voice coil motor; and an image sensor.
 17. A mobile phone comprising the camera module of claim
 16. 18. A voice coil motor comprising: a base unit; a yoke disposed on the base unit; a bobbin disposed in the yoke; a coil and a magnet disposed in the yoke and configured to move the bobbin in an optical axis direction; and an upper elastic member disposed on an upper surface of the bobbin, wherein the bobbin comprises first and second recesses formed on an outer peripheral surface of the bobbin, wherein the second recess is recessed deeper than the first recess with respect to the upper surface of the bobbin, wherein the yoke comprises an inner yoke, wherein at least a portion of the inner yoke is disposed in the second recess, wherein the first recess is disposed next to the second recess so that the first recess is connected to the second recess, wherein the second recess is formed between a plurality of rotation prevention units of the bobbin, and wherein a part of the outer peripheral surface of the bobbin is overlapped by the inner yoke.
 19. The voice coil motor of claim 18, wherein the first recess is configured to decrease a contact area between the rotation prevention unit of the bobbin and the inner yoke when the bobbin is rotated about an optical axis.
 20. The voice coil motor of claim 18, wherein the first recess is overlapped with the inner yoke in a circumferential direction about an optical axis. 